Practitioners in the field of dentistry have long sought polymerizable compositions which would adhere well to dentin. A number of compositions having varying degrees of adhesion to dentin have been reported in the literature, see, e.g., M. Buonocore, W. Wileman, and F. Brudevold, J. Dent. Res., 35, 846 (1956), M. Buonocore and M. Quigley, J. Amer. Dent. Assoc., 57, 807 (1958), M. Anbar and E. Farley, J. Dent. Res., 53, 879 (1974), E. Farley, R. Jones, and M. Anbar, J. Dent. Res., 56, 1943 (1977), R. L. Bowen, E. N. Cobb, and J. E. Rapson, J. Dent. res., 61, 1070 (1982), R. L. Bowen, E. N. Cobb, and L. E. Setz, Denistry 82, 11 (December 1982), U.S. Pat. Nos. 4,182,035, 4,222,780, 4,235,633, 4,259,075, 4,259,117, and 4,368,043, European published patent application No. 0 058 483, and Japanese laid-open patent application (Kokai) Nos. 57-143372 and 57-167364. These compositions generally are used in the form of primers or liners which are applied to dentin in one or more thin coats followed by application of a dental composite, restorative, or adhesive composition to the primer-coated dentin surface.
In recent years, one-part visible light cure compositions have become popular in dentistry, particularly in connection with dental composite, restorative, and adhesive compositions, as these compositions typically are highly loaded with fillers and are difficult to mix with chemical cure polymerization initiators. There has been no particularly pressing need for one-part visible light cured dentin primers, since such primers are low viscosity liquids containing little or no filler content, and can be readily dispensed, mixed, and used in conventional two-part chemical cure formats. There has been relatively little discussion in the literature of visible light cure dentin primers, exceptions being the above-mentioned European patent application No. 0 058 483 (which describes a light-cured dentin primer containing photoinitiators "such as monoketals of aromatic 1,2-diketones or a combination of benzil and a dialkylamino acrylate or methacrylate"), and Japanese laid-open patent application No. 56-120610 (abstracted in Chem. Abs., 95, 225704u (1981)), and said to describe a resin mixture containing diglycidyl methacrylate of Bisphenol A (also known as "BIS-GMA"), triethylene glycol dimethacrylate and 2-methacryloxyethyl phenyl phosphate, which mixture is polymerized in the presence of camphoroquinone and allylthiourea.
Many references describe one-part visible light cure compositions which contain fillers and are suitable for use in dentistry, including U.S. Pat. Nos. 3,709,866 and 4,110,184, and European published patent application Nos. 0 059 649, 0 058 483, and 0 070 634. Other visible light cure compositions said to have more general utility (e.g., as paints or coatings) are disclosed in U.S. Pat. Nos. 3,759,807, 3,926,643, 4,071,424, and 4,089,762. Most of the visible light cure compositions exemplified in the above-mentioned references contain an amine compound which facilitates photopolymerization. Some of the above-mentioned references suggest other compounds which can be used in place of an amine; one reference (U.S. Pat. No. 4,110,184) mentions (without exemplifying) the use of "soluble salts of aromatic sulfinic acids" in place of amines in a filler-loaded visible light cure dental composition.